CN107407810B - Light engine with lenticular microlens array - Google Patents

Abstract

The optical engine includes a pair of lenticular microlens arrays (MLAs) on each side of the polarization converter. Unpolarized light from a source in the engine is focused by the first MLA onto the cells of the polarization converter, which converts the light to a common polarization state to increase efficiency and improve contrast in the system. A half-wave retarder is included on the polarization converter to change the polarization of any light reflected from the downstream optical component to match the polarization of the forward propagating light. The second MLA, which includes a relatively large number of microlens elements, collects light from the polarization converter and highly homogenizes the light as it is received at a downstream imaging panel in a light engine, such as a Liquid Crystal On Silicon (LCOS) panel.

Description

Light engine with lenticular microlens array

Background

The light engine may be used for various imaging applications including, for example, a near-eye display used in a head-mounted display (HMD) device.

This background is provided to introduce a brief context for the summary and detailed description that follows. This background is not intended to be an aid in determining the scope of the claimed subject matter, nor is it intended to limit the claimed subject matter to implementations that solve any or all of the disadvantages or artifacts set forth above.

SUMMARY

The optical engine includes a pair of lenticular microlens arrays (MLAs) on each side of the polarization converter. Unpolarized light from a source in the engine is focused by the first MLA onto the cells of the polarization converter, which converts the light to a common polarization state to increase efficiency and improve contrast in the system. A half-wave retarder is included on the polarization converter to change the polarization of any light reflected from the downstream optical component to match the polarization of the forward propagating light. The second MLA, which includes a relatively large number of microlens elements, collects light from the polarization converter and highly homogenizes the light when received at a downstream imaging panel in a light engine, such as a Liquid Crystal On Silicon (LCOS) panel. In an alternative implementation, the polarization converter is deleted from the optical path and instead a polarization diffraction grating is incorporated into the first MLA to generate polarized light in the system.

By using fewer optical elements to reduce overall system weight and part count, the optical engine provides improved spatial uniformity of the exit pupil and reduced losses compared to conventional arrangements. The thermal load on the system can be reduced while improving power efficiency.

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. It will be appreciated that the above-described subject matter may be implemented as a computer-controlled apparatus, a computer process, a computing system, or as an article of manufacture such as one or more computer-readable storage media. These and various other features will become apparent from a reading of the following detailed description and a review of the associated drawings.

Description of the drawings

FIG. 1 shows a simplified functional block diagram of an optical path through an optical component in a light engine;

FIG. 2 shows a schematic representation of a light engine assembly;

FIG. 3 shows an enlarged view of a light engine assembly;

FIG. 4 shows the optical path from a lenticular MLA focused on a polarization converter;

FIG. 5 shows an incident MLA including a polarization diffraction grating;

FIG. 6 illustrates a light pattern of a conventional light engine at an exit pupil;

FIG. 7 illustrates an improved light pattern for a light engine using a lenticular MLA of the present invention at the exit pupil;

FIG. 8 is a block diagram of an illustrative see-through, mixed reality display device; and

fig. 9 illustrates an exemplary computing system.

Like reference symbols in the various drawings indicate like elements. Elements are not drawn to scale unless otherwise indicated.

Detailed Description

In some applications, exit pupil uniformity in the light engine may be particularly important. For example, in near-eye display applications used in Head Mounted Displays (HMDs) and other devices, if the exit pupil non-uniformity is large, there may be increased spatial non-uniformity at larger field of view (FOV) angles across the display. This non-uniformity may make the user perceive a difference in brightness across the display that changes as the eyes move. This can cause user discomfort and significantly reduce the overall display quality and the immersion in the virtual reality and mixed reality environments in which such devices are typically used.

The light engine of the present invention uses a plurality of lenticular microlens (also commonly referred to as microlens) arrays (MLAs) in the optical path of the light engine. MLAs use an array of substantially cylindrical lenses with apertures typically on the order of microns. The utilization of MLAs can generally improve the operating efficiency of light engines by: increasing the uniformity of light received in an imaging panel of a light engine while reducing optical losses compared to a non-lenticular solution to significantly improve exit pupil uniformity. Improved operating efficiency may result in an overall device configuration that uses less power and has reduced weight, which may be an important criterion for optimization, particularly in HMD applications. In some implementations, improved exit pupil uniformity can reduce variations in light along a waveguide that can be coupled to the exit pupil. In many cases (such as increasing immersion in HMD applications), improved exit pupil uniformity may also be expected to increase user efficiency and enhance the overall quality of the user experience when interacting with the device.

Turning now to the drawings, FIG. 1 shows a simplified functional block diagram of the optical paths (representatively indicated by reference numeral 101) through various optical components in alight engine system 100. Fig. 2 shows the optical assembly in a view, while fig. 3 shows an enlarged view of the MLA and the polarization converter.

It is emphasized that the components shown are illustrative and that various modifications may be made to the components in the optical path and/or their arrangement to suit a particular implementation. The one or morelight sources 102 generate unpolarized (i.e., randomly polarized) light that enters thesystem 100, which typically has a non-uniform angular and spatial distribution, resulting in low brightness uniformity across the range of the exit pupil. The light source may typically comprise one or more LEDs (light emitting diodes), OLEDs (organic light emitting diodes), quantum dots, partially coherent light sources, lasers, etc. One ormore lenses 104, such as a collimating lens, are typically used to collimate and narrow the light emitted from thelight source 102 in a collimated manner.

Afilter 106, such as a dichroic filter or other suitable component, acts as a beam combiner such that primary additive colors (red, green, and blue, collectively "RGB") are included in theoptical path 101. The entrance MLA108 is located where the optical path enters thepolarization converter 110, and the exit MLA 112 is located where the light exits the polarization converter. Polarization converters are typically fabricated using liquid crystals, diffraction gratings, or other suitable techniques to change the polarization state of incident light with some spatial uniformity over a range of wavelengths. An anisotropic birefringent film, which is a half-wave retarder, can be laminated to the back of the polarization converter to change the polarization of any light reflected from downstream optical components in the light engine to match the polarization of the forward propagating light.

Each MLA comprises a substantially rectangular grid of refractive optical elements on a supporting substrate. The refractive optical elements may vary in size and number depending on the implementation. The aperture shape (e.g., whether circular or non-circular) may also vary. MLAs are typically manufactured using lightweight optical grade polymers that can be molded and/or processed (e.g., in primary and/or secondary processes), but glass materials can also be used in some implementations.

Each MLA is configured to focus and converge incoming light on a respective optical component located downstream of theoptical path 101. The microlenses in the array produce a corresponding array of focused light spots, wherein the output array can be controlled according to the microlens shape, optical characteristics, and orientation within the light engine. Thus, in some cases the MLA can be tilted to control the directionality of the output array of focused light.

In this particular illustrative example, the incident MLA 106 focuses and concentrates light onto the light-sensitive cells of thepolarization converter 110. Thus, the configuration of theincident MLA 108 is adapted to the microlens distribution, focal length, and other characteristics that match the polarization converter configuration. Fig. 4 shows thelight path 405 propagating from theincident MLA 108 to thepolarization converter 110, illustrating the focusing effect of the microlens array (only a portion of the array is shown in fig. 4). This implementation helps to improve the efficiency of the system with less loss in the lenticular array (because there are fewer microlens elements). It is possible to enhance the ease of manufacturing while reducing manufacturing errors. Thus, more light is transmitted and focused to thepolarization converter 110.

The configuration of the exit MLA matches the size and resolution of thedownstream imaging panel 128. Thus, theexit MLA 112 typically includes a greater number of microlenses that are more finely distributed in a larger array than theentrance MLA 108.

In alternative implementations, one or both of theMLAs 108 and 112 may be configured to have a substantially flat surface that may be attached to a surface of thepolarization converter 110, for example, using an adhesive and/or mechanical fasteners. This attachment may reduce the need for anti-reflective coatings that may otherwise be used in the gaps between components.

In many cases, the light engine components downstream of the exit MLA may be conventionally arranged. Theaperture element 114 is configured to permit light to enter theprism 116, theprism 116 coupling the light into therelay lens 118, therelay lens 118 magnifying the output array from theexit MLA 112. Themirror 120 reflects the light into anotherrelay lens 122, which relaylens 122 provides additional magnification, with the overall magnification of the relay lens pair being selected to match the size of theimaging panel 128.

Apre-polarizing filter 124 and apolarizing beam splitter 126 are then placed along the optical path, respectively, followed by animaging panel 128. Light from the imaging panel is coupled to anexit pupil 140 using a series of optical elements including one ormore lenses 130, apolarizing filter 132, abeam splitter 133, a set of optics 134 (which may include additional birefringent retarders, lenses, and mirrors), afilter 136, and alens 138. In some applications, the exit pupil may be coupled to awaveguide 150 to guide the output of the light engine to other components and/or systems that may be used for a given application/device (the waveguide is not shown in fig. 2 for clarity of illustration).

Fig. 6 and 7 show a comparison between the uniformity of the light engine output at the exit pupil using a conventional assembly and the lenticular MLA of the present invention. The simplified diagram represents an image that may be captured at the exit pupil using an instrument such as a camera. FIG. 6 shows anillustrative image 600 of the output of a conventional light engine at the exit pupil. FIG. 7 shows anillustrative image 700 of the light output at the exit pupil from a light engine of the present invention having a lenticular MLA. As shown,image 700 includes a more homogenized light pattern having significantly better uniformity across the exit pupil thanimage 600.

FIG. 8 is a block diagram of an illustrative see-through, mixed reality, or virtual reality display system by which the light engine of the present invention may be used in some applications. The display system may take any suitable form, including but not limited to near-eye devices such as those using HMD devices and/or other portable/mobile devices.Display system 800 includes one ormore lenses 802 that form a portion of adisplay subsystem 804 such that an image can be displayed using lenses 802 (e.g., using a projection ontolenses 802, one or more waveguide systems incorporated intolenses 802, and/or in any other suitable manner).Display system 800 further includes one or more outward facingimage sensors 806 configured to acquire images of a background scene and/or physical space being viewed by a user, and may include one ormore microphones 808 configured to detect sound (such as voice commands from a user). Outward facingimage sensor 806 may include one or more depth sensors and/or one or more two-dimensional image sensors. In an alternative arrangement, instead of incorporating a see-through display subsystem, the mixed reality display system may display the mixed reality image in a viewfinder mode of the outward-facing image sensor.

Display system 800 may further include agaze detection subsystem 810 configured to detect a gaze direction or a direction or location of a focal point of each eye of the user, as described above.Gaze detection subsystem 810 may be configured to determine a gaze direction for each eye of a user in any suitable manner. For example, in the illustrative example shown, gazedetection subsystem 810 includes one or more glint sources 812 (such as infrared light sources) configured to cause glints of light to reflect from each of the user's eyes, and one or more image sensors 814 (such as inward facing sensors) configured to capture images of each of the user's eyes. The change in the position of the user's eye and/or pupil, as determined from the image data collected using image sensor(s) 814, may be used to determine the gaze direction.

Further, the location where the gaze line projected from the user's eyes intersects the external display may be used to determine the object (e.g., displayed virtual object and/or real background object) at which the user gazes.Gaze detection subsystem 810 may have any suitable number and arrangement of light sources and image sensors. In some implementations, thegaze detection subsystem 810 may be omitted.

Thedisplay system 800 may also include additional sensors. For example,display system 800 may include a Global Positioning System (GPS)subsystem 816 to allow the location ofdisplay system 800 to be determined. This may help identify real-world objects (such as buildings, etc.) that may be located in the user's contiguous physical environment.

Thedisplay system 800 may further include one or more motion sensors 818 (e.g., inertial, multi-axis gyroscope, or acceleration sensors) to detect movement and position/orientation/pose of the user's head while the user is wearing the system as part of an augmented reality HMD device. The motion data may potentially be used with eye tracking glint data and outward-facing image data for gaze detection and for image stabilization to help correct for blur in the images from outward-facing image sensor(s) 806. The use of motion data may allow changes in gaze location to be tracked even if image data from outward-facing image sensor(s) 806 cannot be resolved.

In addition,motion sensor 818, as well asmicrophone 808 and gazedetection subsystem 810, may also be used as a user input device so that a user may interact withdisplay system 800 via gestures of the eyes, neck, and/or head, and in some cases via voice commands. It will be appreciated that sensors are included for purposes of example, and are not intended to be limiting in any way, as any other suitable sensor and/or combination of sensors may be utilized to meet the needs of a particular implementation of an augmented reality HMD device. For example, biometric sensors (e.g., for detecting heart and respiration rates, blood pressure, brain activity, body temperature, etc.) or environmental sensors (e.g., for detecting temperature, humidity, altitude, UV (ultraviolet) light levels, etc.) may be used in some implementations.

Display system 800 may further include acontroller 820 having alogic subsystem 822 and adata storage subsystem 824 in communication with sensors, gazedetection subsystem 810,display subsystem 804, and/or other components through acommunication subsystem 826. Thecommunication subsystem 826 may also facilitate operation of the display system in connection with remotely located resources such as processing, storage, power, data, and services. That is, in some implementations, the HMD device may be operated as part of a system that may distribute resources and functionality among different components and subsystems.

Storage subsystem 824 may include instructions stored thereon that are executable bylogic subsystem 822 to, for example: receiving and interpreting input from sensors, identifying the user's position and movement, identifying real objects using surface reconstruction and other techniques, and dimming/fading out the display based on distance to the object to allow the object to be seen by the user, among other tasks.

Thedisplay system 800 is configured with one or more audio transducers 828 (e.g., speakers, headphones, etc.) so that audio can be used as part of an augmented reality experience.Power management subsystem 830 may include one ormore batteries 832 and/or a Protection Circuit Module (PCM) and associatedcharger interface 834 and/or a remote power interface for powering components indisplay system 800.

Fig. 9 schematically illustrates a non-limiting embodiment of acomputing system 900 that may be used when implementing one or more of the configurations, arrangements, methods and processes described above. An HMD device may be one non-limiting example ofcomputing system 900.Computing system 900 is shown in simplified form. It will be appreciated that virtually any computer architecture may be used without departing from the scope of the present arrangement. In different embodiments,computing system 900 may take the form of a display device, wearable computing device, mainframe computer, server computer, desktop computer, laptop computer, tablet computer, home entertainment computer, network computing device, gaming device, mobile computing device, mobile communication device (e.g., smartphone), and so forth.

Computing system 900 includes alogic subsystem 902 and astorage subsystem 904.Computing system 900 may optionally include adisplay subsystem 906, aninput subsystem 908, acommunication subsystem 910, and/or other components not shown in fig. 9.

Logic subsystem 902 includes one or more physical devices configured to execute instructions. For example,logic subsystem 902 may be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical constructs. Such instructions may be implemented to perform a task, implement a data type, transform the state of one or more components, or otherwise arrive at a desired result.

Logic subsystem 902 may include one or more processors configured to execute software instructions. Additionally or alternatively,logic subsystem 902 may include one or more hardware or firmware logic machines configured to execute hardware or firmware instructions. The processors oflogic subsystem 902 may be single-core or multi-core, and the programs executing thereon may be configured for serial, parallel, or distributed processing.Logic subsystem 902 may optionally include separate components distributed among two or more devices, which may be remotely located and/or configured for coordinated processing. Aspects oflogic subsystem 902 may be virtualized and executed by remotely accessible networked computing devices configured in a cloud computing configuration.

Storage subsystem 904 includes one or more physical devices configured to hold data and/or instructions executable bylogic subsystem 902 to implement the methods and processes described herein. In implementing such methods and processes, the state ofstorage subsystem 904 may be transformed (e.g., to hold different data).

Memory subsystem 904 may include removable media and/or built-in devices.Storage subsystem 904 may include optical memory devices (e.g., CD (compact disc), DVD (digital versatile disc), HD-DVD (high definition DVD), blu-ray disc, etc.), semiconductor memory devices (e.g., RAM (random access memory), ROM (read only memory), EPROM (erasable programmable ROM), EEPROM (electrically erasable ROM), etc.), and/or magnetic memory devices (e.g., hard disk drive, floppy disk drive, tape drive, MRAM (magnetoresistive RAM), etc.), among others. Thestorage subsystem 904 may include volatile, nonvolatile, dynamic, static, read/write, read-only, random-access, sequential-access, location-addressable, file-addressable, and/or content-addressable devices.

It can be appreciated that thestorage subsystem 904 includes one or more physical devices and excludes the propagated signal itself. However, in some implementations, aspects of the instructions described herein may be propagated by a pure signal (e.g., an electromagnetic signal, an optical signal, etc.) via a communication medium, rather than being stored on a storage device. Furthermore, data and/or other forms of information relating to the present arrangement may be propagated by a pure signal.

In some embodiments, aspects of thelogic subsystem 902 and thestorage subsystem 904 may be integrated together into one or more hardware-logic components by which the functionality described herein is performed. Such hardware logic components may include: for example, Field Programmable Gate Arrays (FPGAs), program and application specific integrated circuits (PASIC/ASIC), program and application specific standard products (PSSP/ASSP), system on a chip (SOC) systems, and Complex Programmable Logic Devices (CPLDs).

When included, thedisplay subsystem 906 may be used to present a visual representation of data held by thestorage subsystem 904. This visual representation may take the form of a Graphical User Interface (GUI). Since the herein described methods and processes change the data held by the storage subsystem, and thus transform the state of the storage subsystem, the state ofdisplay subsystem 906 may likewise be transformed to visually represent changes in the underlying data.Display subsystem 906 may include one or more display devices utilizing virtually any type of technology. In some cases, such display devices may be combined in a shared enclosure withlogic subsystem 902 and/orstorage subsystem 904, or in other cases, such display devices may be peripheral display devices.

When included, theinput subsystem 908 may include or interface with one or more user input devices, such as a keyboard, mouse, touch screen, or game controller. In some embodiments, the input subsystem may include or interface with a selected Natural User Input (NUI) component. Such components may be integrated or peripheral, and the transduction and/or processing of input actions may be processed on-board or off-board. Exemplary NUI components may include a microphone for speech and/or voice recognition; infrared, color, stereo display and/or depth camera for machine vision and/or gesture recognition; a head tracker, eye tracker, accelerometer and/or gyroscope for motion detection and/or intent recognition; and an electric field sensing assembly for assessing brain activity.

When included,communication subsystem 910 may be configured to communicatively couplecomputing system 900 with one or more other computing devices.Communication subsystem 910 may include wired and/or wireless communication devices compatible with one or more different communication protocols. As a non-limiting example, the communication subsystem may be configured for communication via a wireless telephone network or a wired or wireless local or wide area network. In some embodiments, the communication subsystem may allowcomputing system 900 to send and/or receive messages to and/or from other devices using a network, such as the internet.

Various exemplary embodiments of the light engine with a lenticular microlens array of the present invention are now presented for illustrative purposes and are not intended to be an exhaustive list of all embodiments. One example includes a light engine comprising: at least one light source configured to emit light in an unpolarized state with a non-uniform spatial distribution; an incident lenticular microlens array (MLA) positioned along an optical path in the light engine and coupled to receive light from the light source; a polarization converter having an array of polarization converting cells, the polarization converter positioned along the optical path to receive light from the incident lenticular MLA focused on the cells, the polarization converter configured to convert unpolarized light from the source to light having a common polarization state at an output of the polarization converter; and an exit MLA positioned along the optical path to receive the output polarized light from the polarization converter, the exit MLA comprising a microlens array configured to focus light on a downstream imaging panel with improved uniformity of spatial distribution compared to light from the source.

In another example, the light engine further includes a half-wave retarder disposed along the optical path at the output of the polarization converter, the half-wave retarder configured to change a polarization state of light reflected from a downstream optical component to match a polarization of forward propagating light along the optical path. In another example, the half-wave retarder includes a birefringent film disposed as a laminate on the polarization converter. In another example, the light engine further comprises a Liquid Crystal On Silicon (LCOS) imaging panel. In another example, the light engine further includes one or more relay lenses positioned along the optical path between the output of the exit MLA and the imaging panel, the relay lenses applying a magnification factor between the input and the output of the relay lenses. In another example, the light engine further includes an exit pupil at a distal end of the optical path, the exit pupil coupled to receive light from the imaging panel. In another example, the light engine further comprises a waveguide coupled to the exit pupil. In another example, the light engine further includes a collimating lens positioned along the optical path at an output of the source, the collimating lens configured to narrow the emitted light from the source. In another example, the light engine further includes a beam combiner disposed along the optical path at an output of the collimating lens, the beam combiner outputting light comprising a primary color component.

Another example includes an optics subassembly configured for components of a light engine, comprising: a first lenticular microlens array (MLA) positioned along an optical path in the light engine to receive unpolarized light from one or more light sources; a polarization converter positioned downstream of the first lenticular MLA along the optical path and configured to convert the unpolarized light from the one or more light sources to polarized light; a half-wave retarder positioned downstream of the polarization converter along the optical path and configured to change a polarization state of the backward propagating light in the light engine to match a polarization state of the forward propagating light in the light engine; and a second lenticular MLA positioned downstream of the polarization converter along the optical path and coupled to receive polarized light and comprising a plurality of microlenses in an array sized and shaped to expose an imaging panel with focused polarized light having a distribution with increased spatial uniformity for the light from the one or more light sources.

In another example, the first lenticular MLA or the second lenticular MLA is made of molded plastic. In another example, the first lenticular MLA or the second lenticular MLA is made of glass. In another example, in an optics subassembly, angular uniformity of light from the second lenticular MLA is improved for the light from the one or more light sources. In another example, in an optics subassembly, an intensity uniformity of light from the second lenticular MLA is improved for the light from the one or more light sources. In another example, in an optics subassembly, uniformity of light from the second lenticular MLA is improved for the light from the one or more sources.

Yet another example includes a display system comprising: a near-eye display configured to display an image; coupling an image to one or more waveguides in the display; and a light engine configured to generate light for use by an imaging panel configured to generate the image, the light engine comprising: one or more sources configured to emit the light, a first lenticular microlens array (MLA) configured to receive the light as an input and propagate focused light as a first output, a second lenticular microlens array (MLA) configured to receive light from the first output and propagate focused light as a second output, an imaging panel on which the focused light from the second output impinges, and an exit pupil configured to couple light from the imaging panel into the one or more waveguides, the coupled light having increased uniformity as compared to the light emitted from the one or more sources.

In another example, the display system further includes a polarization converter disposed in the optical path between the first and second lenticular MLAs, the polarization converter configured to convert unpolarized light from the one or more light sources into polarized light. In another example, the first lenticular MLA is secured to the polarization converter using an adhesive or a fastener. In another example, the display system further includes a half-wave retarder positioned along an optical path between the polarization converter and the second lenticular MLA. In another example, the half-wave retarder is a film laminated to the polarization converter.

The above-described subject matter is provided by way of illustration only and should not be construed as limiting. Various modifications and changes may be made to the subject matter described herein without following the example embodiments and applications illustrated and described, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.

Claims (19)

1. A light engine, comprising:

at least one light source configured to emit light in an unpolarized state with a non-uniform spatial distribution;

an incident lenticular microlens array positioned along an optical path in the light engine and coupled to receive light from the light source;

A polarization converter having a polarization converting cell array positioned along the optical path to receive light focused on the cells from the incident lenticular microlens array, the polarization converter configured to convert unpolarized light from the light source into light having a common polarization state at an output of the polarization converter, wherein the incident lenticular microlens array is tilted to control a direction in which the light is output downstream to the polarization converter; and

an exit microlens array positioned along the optical path to receive the output polarized light from the polarization converter, the exit microlens array including a microlens array configured to focus light on a downstream imaging panel with improved uniformity of spatial distribution compared to the light from the light source, one or both of the exit microlens array and the entrance lenticular microlens array configured to have a planar surface affixed to a surface of the polarization converter.

2. The light engine of claim 1, further comprising a half-wave retarder disposed along the light path at the output of the polarization converter, the half-wave retarder configured to change a polarization state of light reflected from downstream optical components to match a polarization of forward propagating light along the light path.

3. The light engine of claim 2, wherein the half-wave retarder comprises a birefringent film disposed as a laminate on the polarization converter.

4. The light engine of claim 1, further comprising a Liquid Crystal On Silicon (LCOS) imaging panel.

5. The light engine of claim 1 further comprising one or more relay lenses positioned along the optical path between the output of the exit microlens array and the imaging panel, the relay lenses applying a magnification factor between the input and the output of the relay lenses.

6. The light engine of claim 1 further comprising an exit pupil at a distal end of the optical path, the exit pupil coupled to receive light from the imaging panel.

7. The light engine of claim 6 further comprising a waveguide coupled to the exit pupil.

8. The light engine of claim 1, further comprising a collimating lens positioned along the optical path at an output of the light source, the collimating lens configured to narrow emission light from the light source.

9. The light engine of claim 8 further comprising a beam combiner disposed along the optical path at an output of the collimating lens, the beam combiner outputting light comprising a primary color component.

10. An optics subassembly configured for assembly of a light engine, comprising:

a first lenticular microlens array positioned along an optical path in the light engine to receive unpolarized light from one or more light sources;

a polarization converter positioned downstream of the first lenticular microlens array along the optical path and configured to convert the unpolarized light from the one or more light sources to polarized light, wherein the first lenticular microlens array is tilted to control a direction in which the light is output downstream to the polarization converter;

a half-wave retarder positioned downstream of the polarization converter along the optical path and configured to change a polarization state of the backward propagating light in the light engine to match a polarization state of the forward propagating light in the light engine; and

a second lenticular microlens array positioned downstream of the polarization converter along the optical path and coupled to receive polarized light and comprising a plurality of microlenses in an array sized and shaped to expose an imaging panel with focused polarized light having a distribution with increased spatial uniformity to the light from the one or more light sources, one or both of the second lenticular microlens array and the first lenticular microlens array configured to have a planar surface attached to a surface of the polarization converter.

11. The optical device subassembly of claim 10, wherein the first lenticular microlens array or the second lenticular microlens array is made of molded plastic.

12. The optical device subassembly of claim 10, wherein the first lenticular microlens array or the second lenticular microlens array is made of glass.

13. The optical device sub-assembly of claim 10, wherein angular uniformity of light from the second lenticular microlens array is improved for the light from the one or more light sources.

14. The optical device sub-assembly of claim 10, wherein a brightness uniformity of light from the second lenticular microlens array is improved for the light from the one or more light sources.

15. The optical device sub-assembly of claim 10, wherein uniformity of light from the second lenticular microlens array improves for the light from the one or more light sources.

16. A display system, comprising:

a near-eye display configured to display an image;

Coupling an image to one or more waveguides in the display; and

a light engine configured to generate light for use by an imaging panel configured to generate the image, the light engine comprising:

one or more light sources configured to emit the light,

a polarization converter disposed in the optical path and configured to convert unpolarized light from the one or more light sources into polarized light;

a first lenticular microlens array configured to receive the light as an input and propagate the focused light as a first output,

a second lenticular microlens array configured to receive light from the first output and propagate the focused light as a second output, the second lenticular microlens array being tilted to control a direction in which the light is output downstream toward the one or more waveguides in an optical path between the first and second lenticular microlens arrays, one or both of the second lenticular microlens array and the first lenticular microlens array being configured to have a planar surface attached to a surface of the polarization converter,

An imaging panel upon which focused light from the second output impinges, an

An exit pupil configured to couple light from the imaging panel into the one or more waveguides, the coupled light having increased uniformity as compared to the light emitted from the one or more light sources.

17. The display system of claim 16, wherein the first lenticular microlens array is secured to the polarization converter using an adhesive or a fastener.

18. The display system of claim 16, further comprising a half-wave retarder positioned along an optical path between the polarization converter and the second lenticular microlens array.

19. The display system of claim 18, wherein the half-wave retarder is a film laminated to the polarization converter.

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